With "The Voice" looking awfully lonesome as the sole smash hit on NBC's ratings-challenged schedule, it sounds like a no-brainer for the network to launch another fresh reality competition.

With “The Voice” looking awfully lonesome as the sole smash hit on NBC’s ratings-challenged schedule, it sounds like a no-brainer for the network to launch another fresh reality competition. But retail chic throwdown “Fashion Star” instantly appears more limited in its appeal — the size of its niche dependent on how well viewers take to the opportunity to buy clothes from competing designers within 24 hours of seeing them on TV.

It’s easy to imagine the pitch: Think “Project Runway” transformed into “American Idol” and focused on fashionable, but wearable, designs made immediately available for purchase in major retailers.

By securing the participation of Macy’s, Saks Fifth Avenue and H&M, “Fashion Star” covers the bases of potential customers — budget to high-end — and takes exec producer Ben Silverman’s fondness for product placement to new levels. The whole show is a commercial, from slickly executed runway presentations scored with pulsating pop songs to famous faces Jessica Simpson and Nicole Richie shilling for winning designs under the guise of “expert” commentary.

The glossy you-won’t-see-this-on-cable production values support a relatively straightforward competition structure, whittling down 14 contestants until a single winner emerges. Instead of a record contract or ballroom trophy, the victor receives $6 million in orders for capsule collections in the three retailers. Each week the competing designers vie for a smaller prize, presenting a different piece from their line in front of designated “mentors” (Simpson, Richie and designer John Varvatos) and buyers from the retail chains (Caprice Willard for Macy’s, Terron E. Schaefer for Saks Fifth Avenue and Nicole Christie for H&M).

If one of the buyers likes a designer’s work enough to make a purchase, the showcased item goes on sale immediately online and the following day in stores (filming took place last summer, allowing ample time to pull off this minor feat of synergy). If the buyers don’t bite, the designer is up for elimination.

Unlike the personality clashes and cutthroat drama that drives “Project Runway,” “Fashion Star’s” format hews much closer to the performance-first emphasis of “American Idol” or “The Voice.” The contestants rarely interact with each other and are defined by tidy back stories — male model, El Salvadorian immigrant, cancer survivor — briefly detailed before their presentations.

Splitting the judging duties between the mentors and the buyers provides welcome options in commentary — Simpson may think something is cute, but Saks only cares if it will sell — but also prevents a definitive voice of authority from emerging à la Simon Cowell. As the host, Elle Macpherson doesn’t add much beyond supermodel glamour and one good dig at a contestant’s “Aussie chauvinism.”

After a 90-minute premiere, NBC has made the rather odd decision to schedule the series at 10 p.m., a difficult timeslot broadcasters have never really cracked with reality. Although it faces marginal competition, the slot further underscores the likely limits of “Fashion Star’s” glow.